King for a Day. Mia, Vincent and Paula go for ice cream, where they meet a handsome young prince who resembles a real-life Mo. As he begins to take a shining to Mia, Vincent can barely conceal his seething jealousy. But duty calls in Centopia, where Mo himself has been given a thrilling duty: to stand in as ruler of Centopia while the king and queen have the flu. But when Mia and Yuko are cornered by Gargona and her munc minions, Mo must leave his post and find a way to return them to safety.